The present invention is directed to a high density electrical interconnection device and method therefor and more particularly to an apparatus and method utilizing a thieving pattern.
In the printed circuit board (PCB) industry where the PCB carried electrical conductors (such as copper) to interconnect the various devices, it has been the practice to manually or automatically add large pieces of metal pattern (called "thieving") where the signal conductors were not present. This is intended to make the plating more uniform. In other words, during deposition the distribution of current density and the processing of the electroplating is thus made more uniform.
The foregoing problem is exacerbated or is more critical in a high density electrical connecting structure which is utilized for example to interconnect components (generally integrated circuits or ICs) of high performance digital computers. These structures include multiple layers consisting of conductors disposed in a polymer matrix. Such a high density signal carrier (HDSC) is disclosed in a U.S. application, Ser. No. 055,794, entitled "Method of Forming a Multi-Level Interconnection Device," filed Jun. 1, 1987, in the name of Ho, et al., and assigned to the assignee of the present application.
In addition to the foregoing application, interconnection techniques and structures for interconnecting IC chips on a chip carrier, which includes metallic conductors and polymer materials are also shown in U.S. Pat. No. 4,480,288 to Gazdik, et al., and 4,650,545 to Laakso, et al. In fact, the Gazdik patent discusses a technique for compensating for thermal mismatch between the chip and substrate. This problem is made much more critical in a high density signal carrier structure with which the present invention is especially useful.